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    Subject[53/55] fs: call security_d_instantiate in d_obtain_alias V2
    2.6.37-stable review patch.  If anyone has any objections, please let us know.


    From: Josef Bacik <>

    commit 24ff6663ccfdaf088dfa7acae489cb11ed4f43c4 upstream.

    While trying to track down some NFS problems with BTRFS, I kept noticing I was
    getting -EACCESS for no apparent reason. Eric Paris and printk() helped me
    figure out that it was SELinux that was giving me grief, with the following

    type=AVC msg=audit(1290013638.413:95): avc: denied { 0x800000 } for pid=1772
    comm="nfsd" name="" dev=sda1 ino=256 scontext=system_u:system_r:kernel_t:s0
    tcontext=system_u:object_r:unlabeled_t:s0 tclass=file

    Turns out this is because in d_obtain_alias if we can't find an alias we create
    one and do all the normal instantiation stuff, but we don't do the

    Usually we are protected from getting a hashed dentry that hasn't yet run
    security_d_instantiate() by the parent's i_mutex, but obviously this isn't an
    option there, so in order to deal with the case that a second thread comes in
    and finds our new dentry before we get to run security_d_instantiate(), we go
    ahead and call it if we find a dentry already. Eric assures me that this is ok
    as the code checks to see if the dentry has been initialized already so calling
    security_d_instantiate() against the same dentry multiple times is ok. With
    this patch I'm no longer getting errant -EACCESS values.

    Signed-off-by: Josef Bacik <>
    Signed-off-by: Al Viro <>
    Cc: Chuck Ebbert <>
    Signed-off-by: Greg Kroah-Hartman <>

    fs/dcache.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/fs/dcache.c
    +++ b/fs/dcache.c
    @@ -1201,9 +1201,12 @@ struct dentry *d_obtain_alias(struct ino

    + security_d_instantiate(tmp, inode);
    return tmp;

    + if (res && !IS_ERR(res))
    + security_d_instantiate(res, inode);
    return res;

     \ /
      Last update: 2011-03-26 00:59    [W:0.020 / U:117.116 seconds]
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